How does C ++ define an array with the number of unknown elements ?, Number Array

How does C ++ define an array with the number of unknown elements ?, Number Array

1. Dynamic Memory Allocation

C ++ dynamic memory application:

Int arraySize; // defines the number of elements.

Cin> arraySize; // number of input Elements

Int * p; // pointer to an array

P = new int [arraySize]; // dynamically allocates memory.

...

Delete [] p; // finally releases the memory space

C language dynamic memory application:

Int arraySize; // defines the number of elements.

Scanf ("% d", & arraySize); // number of input Elements

Int * p; // pointer to an array

P = (int *) malloc (arraySize * sizeof (int) // dynamically allocate memory

...

Free (p); // finally releases the memory space

2. vector

Vector is the Vector provided in C ++ STL.

The vector size can be dynamically changed.

The vector can access elements through subscript

You can use push_back to add elements to the vector and change the size.

# Include

Vector MyArray;

// You can use myArray. push_back (integer); to add elements based on data requirements. // you can use subscript to access Vector elements.